VICTORIA — A glut of new documents is undermining an approval deadline for the proposed $36 billion Pacific NorthWest liquefied natural gas project planned for British Columbia's northern coast.

Statements from the Canadian Environmental Assessment Agency and federal Environment Minister Catherine McKenna say it's premature to expect an answer for the Pacific NorthWest LNG plant by the March 22 deadline.

That date is when McKenna can make an environmental approval decision herself or refer the plan to cabinet, but both the minister and the environmental assessment agency are signalling more work needs to be done.

The environmental assessment agency issued a draft report last month concluding the plant could be built without major environmental impacts, but it's currently reviewing 34,000 public comments on the review and 11,000 pages of technical data.

Pacific NorthWest, which is backed by Malaysian-owned energy giant Petronas, submitted new information this month to the agency that estimates the total greenhouse gas emissions from the project, including upstream emission estimates from pipelines and gas extraction.

Premier Christy Clark says she told Prime Minister Justin Trudeau the project will be Canada's largest contribution to fighting climate change if it can sell cleaner burning natural gas to China.